1.
x+1/x=5
x^2+1/x^2=3
(x+1/x)^3=125
x^3+3(x+1/x)+1/x^3=125
x^3+1/x^3=110
2.
4^x=2^(3x+1)
2x=3x+1
x=-1
3.
(换底公式）
log(2)9×log(3)根号5×log(5)2
=2lg3÷lg2×1/2lg5÷lg3×lg2÷lg5
=1